Effect of early sodium supplementation on weight gain of very preterm infants: a randomised controlled trial

BACKGROUND AND OBJECTIVES: Preterm neonates are at risk of impaired growth. Hyponatraemia in preterm neonates is due to renal immaturity and can lead to growth failure. We aimed to assess the effect of early enteral sodium supplementation on weight gain velocity from birth to 34 weeks postmenstrual age in preterm neonates. METHODS: In this double-blinded randomised controlled trial, we recruited neonates born between 25 weeks and 30 weeks+6 days of gestation who received a minimum feed volume of 100 mL/kg/day before 10 days of life. In the intervention group, 4 mEq/kg/day of oral sodium was administered using 15% saline and, in the control group, normal saline was given as a placebo. The primary outcome was mean weight gain velocity in g/kg/day. RESULTS: A total of 104 neonates were recruited with 52 infants in each group. Mean (SD) weight gain velocity (g/kg/day) was significantly greater in intervention than in control group (18.0±4.4 vs 14.4±3.9; mean difference 3.6 with 95% CI 2.04 to 5.27, p<0.001). Linear growth (cm/week) was greater in intervention than in control group (0.88±0.18 vs 0.73±0.28 cm/week; mean difference 0.14 with 95% CI 0.05 to 0.24, p=0.04). Subgroup analysis in extreme preterm showed similar results. There was no significant difference in head growth or clinical outcomes between the groups. CONCLUSION: Early postnatal sodium supplementation improves in-hospital weight gain and linear growth in very preterm neonates.